Optimized arm string routines

[Richard Earnshaw]

On Tue, 2009-01-20 at 10:21 +0000, Richard Earnshaw wrote:
> I've recently written the following hand-optimized versions of the
> string functions strlen, strcpy and strcmp for ARM (including support
> for thumb1 and thumb2).  These are attached for inclusion in newlib.
> 
> They should perform significantly better than the C coded versions since
> they invariably use fewer call-saved registers (a major overhead on
> short strings).  They also handle more cases than the C versions before
> falling back to simple byte loops.
> 
> The thumb1 variants are all optimized for space.  The inner loops become
> very complex with the restricted instruction set and it's unlikely to
> give any significant performance benefit. 
> 
> R.
> 
> <date>  Richard Earnshaw  <rearnsha@arm.com>
> 
> 	* libc/machine/arm/arm_asm.h: New file.
> 	* libc/machine/arm/strlen.c: New file.
> 	* libc/machine/arm/strcpy.c: New file.
> 	* libc/machine/arm/strcmp.c: New file.
> 	* libc/machine/arm/Makefile.am: Add new string routines.
> 
> 

Whops, the strcpy routine had a bug in it, which I managed to introduce
late yesterday during final tweaking :-(

Please use this version rather than the one in the original patch

R.
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